The present invention relates in general to surgical instruments which are used to puncture tissue walls for the performance of endoscopic surgery within body cavities, organs, joints and the like covered by the tissue walls and, more particularly, to such surgical instruments or trocars which permit viewing the tissue walls during wall puncturing operations to help prevent injury to structures within the tissue walls and fields of operation beyond the tissue walls.
Endoscopic surgical procedures have become widely accepted. These procedures permit surgeons to employ a wide variety of endoscopic instruments with minimal incisions into the skin and tissue surrounding a body cavity or other targeted interior surgical site. In order to introduce these endoscopic surgical instruments into an interior surgical site, it is necessary to first puncture and cannulate the site using an initial surgical instrument known as a trocar.
Conventional trocars consist of a trocar obturator and a trocar cannula. A manual obturator may have a sharp pointed end which serves to pierce body tissue and to widen the resulting opening to the width of the obturator and cannula which is carried along with the obturator. Alternately, while still piercing body tissue and widening the resulting opening, a radio frequency (rf) obturator may have one or more electrodes associated with its distal end such that rf energy can be applied to the electrodes and effect tissue cutting.
In either event, the insertion of a trocar, particularly a first trocar, even with the skilled selection of a penetration site, involves a risk of damaging blood vessels at the site. There is further risk of damage to vessels, organs and other interior structures after penetration of the tissue wall. In the case of the abdomen, the small intestine and omentum majus are especially at risk if adhesions and concretions with the anterior abdominal wall are present since during penetration of the abdominal wall, structures adhering thereto may be pierced before the trocar enters free abdominal space.
To reduce the risk of damage, particularly to the intestine and omentum majus, a hollow needle can be passed through the abdominal wall while the abdominal wall is lifted to introduce gas into the abdominal cavity and thereby extend the abdominal wall away from the underlying omentum majus and intestine for insertion of a trocar. Even then there is residual risk of damage during insertion of the hollow needle and trocar.
While trocars must be capable of penetrating tissue walls to cannulate a targeted surgical site, a variety of safety trocars have been developed which serve to protect vessels, organs and other structures within a body cavity. For example, a spring-loaded shield may be associated with the cutting tip of a manual obturator such that the shield springs forward to shield the cutting tip as soon as the tip penetrates a tissue wall.
A second approach to protecting against damage which can be done by trocar insertion is to associate optics with a trocar such that insertion of the trocar can be guided based on images of the penetration site. Optics are disclosed for use in a manual trocar obturator in published European Patent Application No. 0484725 A1.
The trocar disclosed in the noted European Patent Application includes a hollow shaft which terminates in a hollow conical window. An optic is inserted down the hollow shaft and terminates at an axial distance from the summit or point of the hollow conical window such that the entire window can be illuminated and viewed by the optic. A second optic may be run laterally passed the first optic to a window-forming point at the summit or point of the conical window such that the advance of the trocar can be viewed. The first and second optics are disclosed as preferably being wide-angle or fish-eye optics. If both optics are provided, the operator can obtain a feeling for the path and rate of advance, and also observe the structures lying in front of the point to avoid damage as the trocar is inserted.
Optics are disclosed for use in a rf trocar in U.S. Pat. No. 5,221,281 wherein a longitudinal circular channel is formed in an electrosurgical tubular trocar through which an optical catheter can be passed. The tubular trocar includes an electrode and a conductor at its distal end for bipolar operation of the trocar.
Provision of a fiber optical cable in a trocar obturator is suggested in International Patent Application No. PCT/US92/01225. However, the structure of this obturator is unclear since the specification refers to reference numerals and structure which is not shown in corresponding drawings.
Since the view provided by the hollow optical window in the noted European Patent Application may be distorted and the electrosurgical cutting operation may interfere with the view provided by the optical catheter of the '281 patent, there is a need for surgical apparatus for inserting a cannula through tissue defining a wall of a body cavity which reduces the risk of possible damage to vessels, organs and the like via improved optic control of the apparatus.